<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        div{
            font-size: 20px;
            color: red!important;
        }
        .hello{
            font-weight: bold;
            color: blue;
        }
        #world{
            text-decoration: underline;
            color: green;
        }

        p{
            color: red;
        }
    </style>
    <link rel="stylesheet" href="css/style.css">
</head>
<body>
    <div class="hello" id="world" style="background: #ccc; color: cyan;">
        哈哈哈哈
    </div>

    <p>
        嘻嘻嘻嘻
    </p>
</body>
</html>